"I could be neurotic, bohemian and all over the place; she always had to be so correct," Simon told People of their friendship. "I was who she wasn’t. I think she got a big kick out of that."

Being tight with Jackie meant that Simon was privy to her candid thoughts, whether they be about Jackie's own past loves, or her son's current flame.

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Jackie was apparently concerned about some of JFK Jr.'s decisions. "Jackie was very consumed with getting him on the right path," Simon recalls. "She didn’t approve of some of [the women]—she was horrified by Madonna.”

When Simon spoke with Jackie about JFK's infidelity, Jackie said that "understood that he made some stupid mistakes." But according to Simon, at the end of the day Jackie was able to overlook her husband's extramarital relationships because "she knew he loved her more, much more."

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Jackie later wed Aristotle Onassis, and her feelings toward him (at least at the time that Simon knew her) seem more mixed. "She said he was very sexy—he would sing to her on his yacht and take her great places to make love," Simon says. "She knew marrying him was the bad-girl move. In a way I never knew whether she was sticking up for her own decision or whether she really loved him."

Simon notes that their friendship wasn't always consumed by serious conversations; the musician claims that Jackie could be "incredibly funny." Simon recalled one time, after the pair had met opera singer Plácido Domingo, that the former first lady tricked her into thinking he'd sent her a letter and photograph.

"She’d written it herself and disguised her handwriting!" Simon says. "The practical joker in her was nonstop."